Can I submit a partial refund?

[aether_gems]

A buyer decided to cancel 30 minutes after submitting payment. I saw the request a few hours later and submitted for a refund. Despite having done it only a few hours later, it said there was an issue with the cancellation and I have to submit the refund manually through PayPal. In my experience, this means I have to pay for the PayPal fees because they do not refund those. I would not have accepted the cancellation if I knew their carelessness would cost me. Can I submit to only refund their payment minus the fees it cost me to receive it?